From the University of Leeds , 250 million year old certainty where there was none before, now megasized.
Tropical collapse caused by lethal heat
Extreme temperatures blamed for ‘Dead Zone’
Scientists have discovered why the ‘broken world’ following the worst extinction of all time lasted so long – it was simply too hot to survive.
The end-Permian mass extinction, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world’s species. Typically, a mass extinction is followed by a ‘dead zone’ during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early Triassic period which followed, lasted for a perplexingly long period: five million years.
A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.
Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: “Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years.”
It is also the first study to show water temperatures close to the ocean’s surface can reach 40°C – a near-lethal value at which marine life dies and photosynthesis stops. Until now, climate modellers have assumed sea-surface temperatures cannot surpass 30°C. The findings may help us understand future climate change patterns.
The dead zone would have been a strange world – very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat.
Before the end-Permian mass extinction the Earth had teemed with plants and animals including primitive reptiles and amphibians, and a wide variety of sea creatures including coral and sea lillies.
This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.
The study, published today [19 October 2012] in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date.
Sun and his colleagues collected data from 15,000 ancient conodonts (tiny teeth of extinct eel-like fishes) extracted from two tonnes of rocks from South China. Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.
Professor Paul Wignall from the School of Earth and Environment at the University of Leeds, one of the study’s co-authors, said: “Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won’t get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover.”
The study is the latest collaboration in a 20-year research partnership between the University of Leeds and China University of Geosciences in Wuhan. It was funded by the Chinese Science Foundation.
For more information:
‘Lethally hot temperatures during the early Triassic greenhouse’ by Yadong Sun (University of Leeds and China University of Geosciences), Michael Joachimski (University Erlangen-Nurnberg, Germany), Paul B. Wignall (University of Leeds), Chunbo Yan (China University of Geosciences), Yanlong Chen (University of Graz, Austria), Haishui Jiang (China University of Geosciences, Lina Wang (China University of Geosciences) and Xulong Lai (China University of Geosciences) is published in Science on 19 October 2012. For a copy please view the web page http://www.eurekalert.org/jrnls/sci/ or contact the Science press team, phone +1 202-326-6440 or email scipak@aaas.org
For interviews please contact Esther Harward, University of Leeds press office, phone +44 113 343 4196 or email e.harward@leeds.ac.uk
Does anybody remember when Asteroids where the culprits du-jour and the Permian extinction plus lack of new species blamed on them?
“This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.”
Seems like a rather bizarre claim! Do they have proof, or is this just wishful thinking?
It is also the first study to show water temperatures close to the ocean’s surface can reach 40°C –
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Looks like you’re right guys. The science is not settled.
This is ridiculous.
That 50 to 60 degrees might be uninhabitable for most mamals, doesn’t mean we should be afraid of the sunrise, which can cause temperature increases of 30 degrees, nor the moderate rises in temperature that occurred from 1980 to the mid 90’s.
The whole thing is one big non sequitur.
So, are they saying that the broken CO2 cycle caused the extinction, or that it caused the 5 million year gap in tropical life? Seems to me that any discussion about this extinction event and subsequent re-start has to include a mention of the Siberian Traps.
“Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won’t get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover.”
Is this Professor Wignall’s way of saying it’s worse than we thought?
Shame the seas were only a few inches deep back then, else the cooler water below would have been a refuge too.
At that time atmospheric CO2 levels were falling from the 8000ppmv of the Ordovician, with its prolonged ice age, so if temperatures were rising then CO2 may not be the culprit. As for hot sea water, I have seen fish swim in the very shallow waters round Bahrein with temperatures really too hot for me to swim though they were small fish and quite lethargic due to low O2 levels. There would certainly be a species quiet period after a mass extinction as the survivors sorted out a new food chain and sourced feeding areas but any mass extinction would not happen over night but over a period of perhaps thousands of years but certainly hundreds.
How good is the temperature versus oxygen isotope correlation?
(I should know after following this site for so many moons.)
Nothing but ferns and shrubs on land? How did they survive? And why didn’t they proliferate and “take over”?
I suspect logic leaps and lapses.
begs the question what caused the release of all that carbon in the first place, dino farts?
“Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.”
Beyond about 540ppm CO2 levels would make no difference, plus one would have to assume relative humidity in that era was > 10% which would mask any CO2 effect anyway.
Whatever caused this temperature rise, it could not have been CO2.
“levels of Co2 can rise unchecked, which causes temperatures to increase”
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And pain causes tumors, so we can treat cancer with aspirin. We can only pray that the curative magic of aspirin has no plateau at a relatively low level.
I’ve probably misunderstood this, but they seem to be saying that rising CO2 levels caused the temperature rise, but that the rise in temperature caused the plants and animals to die so that the CO2 was not sequestered …?
I’d love to see the paper. My first instinct is to think its ridiculous to believe they can use oxygen isotopes to determine climate when the world was so different. Who knows what the weather patterns and ocean currents that existed at the time were doing? Also what other factors were involved in the O2 isotope redistributions at the time of the mass extinction? And how did this effect their determination of temperature vs isotope ratio?
And the one bugbear that always annoys me is that they always paint the “it was the warming (by CO2) what did it” but never go on to suggest the mechanism for coming back from that situation.
And of course did they really paint that global doom picture from a single proxy, in a single region? Ouch.
New science PhD degrees have apparently joined their colleagues over in Sociology as being nothing more than a bad joke at public expense. Redefining “dumb” (PhDs from the 80s through 2000s) and “dumber” (graduate students of those foementioned PhDs). A complete collapse of western rational education.
So on the one hand you have “extreme” temperatures and no fish alive in the tropics and then on the other they are sampling teeth from these same non-existent fish…..
…or is this just another unprecedented extreme extrapolation from a non-proven hypothesis?
Coral and shellfish survived? I thought the CO2 was causing them to die.
I hate to say this, but if the data are from two tons of rock from just one place, isn’t this a bit like taking rings from just one tree?
Edited to add: the Ph.D needs to be redefined as the Cb.D – “Doctor of Confirmation Bias”.
“The dead zone would have been a strange world – very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures”
So the zone wasn’t dead then. It was like the Sahel, more or less.
‘This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.’
In other words, NOT likely to happen again.
Not that they will bother to mention that part.
So we had fish and conodont animals in the dead zone, according to that map. I will wait to read the paper, but colour me skeptical.
John Gorter
Looks like that world would have no global ocean circulation, no way to dump heat at the poles as is the current set up. Not the same world….
Confirmation bias at its worst. The *only* thing that can be said is that the proxy indicated higher temperatures – the rest is conjecture.